I picked up a Apollo 500 amplifier at the MIS hamfest it is in great condition and works perfectly. It is a 6 tube amplifier that has 6lf6 tubes in it. I cannot find any information anywhere about this amplifier has anyone seen or heard of this model amplifier?? I tried to unload picture but cannot.
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Apollo 500 amplifier
- Thread starter Jimbo165
- Start date
The CB Tricks web site shows only a picture of the front.
Never have seen a diagram for this one.
73
Never have seen a diagram for this one.
73
Looks more like one (on its side) driving three.
To that I would add that any amplifier with a single driver tube is meant for a SMALL radio. When it was designed, that's all there was. A "black" base radio with two final transistors will typically overwhelm a single driver tube on modulation, no matter how low you set the carrier power.
The other outstanding characteristic about this kind of amplifier was the tendency to blow out one of the two power transformers. Don't know exactly why, but we saw it over and over. Whoever made this one also sold them under other names as well. Pretty sure "Firebird" was one of them. Just be nice to it.
73
To that I would add that any amplifier with a single driver tube is meant for a SMALL radio. When it was designed, that's all there was. A "black" base radio with two final transistors will typically overwhelm a single driver tube on modulation, no matter how low you set the carrier power.
The other outstanding characteristic about this kind of amplifier was the tendency to blow out one of the two power transformers. Don't know exactly why, but we saw it over and over. Whoever made this one also sold them under other names as well. Pretty sure "Firebird" was one of them. Just be nice to it.
73
The Apollo 500 I have is not the one on cb tricks I had one of those types also at one time. This is a 6 tube and design completely different. I just cannot put a picture on here for some reason so you could see real amp. When I go to pictures just has a insert photo and nothing else?? The amp has 3 tuning knobs.
Cool
2x driving 4. GG AB1. Plate voltage. Most likely is around 700v. Only 2 HV caps in series.
Grid tune. Similar to early grey D&A amps."SWR" input impedance matching device.
In this configuration. Provided it is driven with 3.5W to 4. Those 6LF6's will last awhile.
Separate filament transformer. Main, Iron HV tranny looks like a Television style tranny.
Judging by the orange Z-14 RF chokes & the classic D&A grid tune; 12v relay. Made
about the same time as the Beige Brown D&A's. 1970. Early Palomar Skippers with
6LF6. 6LF6's became scarce around 1975. I have never seen this model before.
Most likely only a few were made. Could be a proto type never put into production.
Thanks for the PICS !
four fingers & a thumb !
2x driving 4. GG AB1. Plate voltage. Most likely is around 700v. Only 2 HV caps in series.
Grid tune. Similar to early grey D&A amps."SWR" input impedance matching device.
In this configuration. Provided it is driven with 3.5W to 4. Those 6LF6's will last awhile.
Separate filament transformer. Main, Iron HV tranny looks like a Television style tranny.
Judging by the orange Z-14 RF chokes & the classic D&A grid tune; 12v relay. Made
about the same time as the Beige Brown D&A's. 1970. Early Palomar Skippers with
6LF6. 6LF6's became scarce around 1975. I have never seen this model before.
Most likely only a few were made. Could be a proto type never put into production.
Thanks for the PICS !
four fingers & a thumb !
Thanks giboni it is a nice amp and I do not know how it does it over 1000 watts pep easy. Stray rf could be affecting my watt meter possibly causing increased number. Using a galaxy 44v mobile 2 watt dead key radio swinging to 20 watt pep. I like amp because it is made of all aluminum and will never rust anywhere. Dainbramage fully meshed because was cleaning inside of amp when picture taken.
1000w AM PEP
If I understand it correctly. Is 4 x 250W RMS. A Palomar Skipper 300. With 1x 3 x short
6LF6/8950. 3.5 watts to 4 in. Dead keys 300w RMS. AM PEP is 1200w.
Most likely. The original band this Amp was configured for. Is not 11 meters.
The Skipper if I remember. Is about 800v DC under load at the plate.
The no load voltages. Or "Peak" voltages are always much higher. Skipper uses 3 x
450v in series total 1350v. Higher than the peak.
Sweep tubes are getting pricy. 6LF6 is very pricy ! So running conservative is the way to
go for most people. I think. Like the Skipper. Your box is not chained to 6LF6 for FUEL.
A separate filament transformer makes them versatile. Simply swap them out for
whatever 12 pin Beam Compactrons U may have. 20LF6, 27LF6, 26LX6,
30KD6,36KD6,
30MB6. 8950(13v) which is the same as 6LX6(6.3v). Even M-2057. LF6 is really the
best though.
Up to 1.2 amps at the plate. 40-50 watts plate dissipation. M-2057. I am not a 100%
sure it is actually a compactron version of the 8908. 2.5 Amps at the plate. Easily 50
watts at the plate. I will find out one day. 30 M-2057. But no 8908 ugh.
I cannot tell how large your plate transformer is or heavy. U can estimate the KVA by
the weight. Push 3.5 W into it ? The Skippers will do 450w RMS with 8w in.
With 6LF6 this was not an issue. Anything else EG 8950 LX6. U have to keep the keyup
shorts. So U don't black toast the tubes. Even with 6LF6. It had to be short. The main
iron would short out & be destroyed.
Have fun !
4fingers&aThumb
Ah didn't notice your question.
When I go about the Art of fabricating RF tank coils.
I start with my favorite frequency. 27.385. Sweep tubes especially LQ6. Are notorious
for there low output impedances in parallel.
To directly answer your question. I personally am uncomfortable with a Load & tune that
are Maxed out in any way. I keep playing. Until I arrive at full output. Additionally.
I have to see play in the load & tune variable capacitors. Circuit Q ought to be very close to 12.
The main tank coil minimum Q of 10. Maximum Q of 15. I do not use solid wire. 13-14 seems to be
optimum for the sweeps I have played with.
I use 1/16 OD up to 3/8 OD tubing. Nickel or silver plated.
Its possible to have several different Tank Coils that will work. Only one. The right one.
It will have a large frequency tuning range at Full output. Driver tanks ? I've read from the
Ham guru's. A Q of 2 ? My experience with Sweep tubes says different. But. the Hams were working
with very large triodes & tetrodes & non Beam pentodes ?
If U R getting 250W RMS. 2w in 700v at the plate. Assuming it does this from channel 1 to 40.
Sounds about right. Without a good Inductance meter. LCR. It is nearly impossible to fabricate RF
tank coils for Sweep tubes. It can be done. If you quit your day Job ? trial & error ?
4fingers&aThumb
If I understand it correctly. Is 4 x 250W RMS. A Palomar Skipper 300. With 1x 3 x short
6LF6/8950. 3.5 watts to 4 in. Dead keys 300w RMS. AM PEP is 1200w.
Most likely. The original band this Amp was configured for. Is not 11 meters.
The Skipper if I remember. Is about 800v DC under load at the plate.
The no load voltages. Or "Peak" voltages are always much higher. Skipper uses 3 x
450v in series total 1350v. Higher than the peak.
Sweep tubes are getting pricy. 6LF6 is very pricy ! So running conservative is the way to
go for most people. I think. Like the Skipper. Your box is not chained to 6LF6 for FUEL.
A separate filament transformer makes them versatile. Simply swap them out for
whatever 12 pin Beam Compactrons U may have. 20LF6, 27LF6, 26LX6,
30KD6,36KD6,
30MB6. 8950(13v) which is the same as 6LX6(6.3v). Even M-2057. LF6 is really the
best though.
Up to 1.2 amps at the plate. 40-50 watts plate dissipation. M-2057. I am not a 100%
sure it is actually a compactron version of the 8908. 2.5 Amps at the plate. Easily 50
watts at the plate. I will find out one day. 30 M-2057. But no 8908 ugh.
I cannot tell how large your plate transformer is or heavy. U can estimate the KVA by
the weight. Push 3.5 W into it ? The Skippers will do 450w RMS with 8w in.
With 6LF6 this was not an issue. Anything else EG 8950 LX6. U have to keep the keyup
shorts. So U don't black toast the tubes. Even with 6LF6. It had to be short. The main
iron would short out & be destroyed.
Have fun !
4fingers&aThumb
Ah didn't notice your question.
When I go about the Art of fabricating RF tank coils.
I start with my favorite frequency. 27.385. Sweep tubes especially LQ6. Are notorious
for there low output impedances in parallel.
To directly answer your question. I personally am uncomfortable with a Load & tune that
are Maxed out in any way. I keep playing. Until I arrive at full output. Additionally.
I have to see play in the load & tune variable capacitors. Circuit Q ought to be very close to 12.
The main tank coil minimum Q of 10. Maximum Q of 15. I do not use solid wire. 13-14 seems to be
optimum for the sweeps I have played with.
I use 1/16 OD up to 3/8 OD tubing. Nickel or silver plated.
Its possible to have several different Tank Coils that will work. Only one. The right one.
It will have a large frequency tuning range at Full output. Driver tanks ? I've read from the
Ham guru's. A Q of 2 ? My experience with Sweep tubes says different. But. the Hams were working
with very large triodes & tetrodes & non Beam pentodes ?
If U R getting 250W RMS. 2w in 700v at the plate. Assuming it does this from channel 1 to 40.
Sounds about right. Without a good Inductance meter. LCR. It is nearly impossible to fabricate RF
tank coils for Sweep tubes. It can be done. If you quit your day Job ? trial & error ?
4fingers&aThumb
Last edited:
Shoosh instead of editing.
How R U loading & tuning the Amp ?
R U using a watt meter on the RMS position ?
If so. What is the RMS watts ?
Properly loading tuning an Amp is by RMS. Not PEP. Tubes or other components
in the Amp will be damaged if you are adjusting based on PEP !
How R U loading & tuning the Amp ?
R U using a watt meter on the RMS position ?
If so. What is the RMS watts ?
Properly loading tuning an Amp is by RMS. Not PEP. Tubes or other components
in the Amp will be damaged if you are adjusting based on PEP !
Experts I have some questions.......For the Apollo 500 X-2,when tuned up with 2 watts from the radio...
#1...What would be the dead key on the amp be?..
# 2...Can you adjust the coils for more output ?
# 3...What would final output from the amp be? 400 watts?
THANKS TO THE EXPERTS
#1...What would be the dead key on the amp be?..
# 2...Can you adjust the coils for more output ?
# 3...What would final output from the amp be? 400 watts?
THANKS TO THE EXPERTS